Alternating-current frequency-meter



J. G. BLESSING- ALTERNATING CURRENT FREQUENCY METER. APPLICATION FILED FEB. 19. 1917.

-"1 355,884. V Patented Oct. 19,1920.

2 SHEETSSHEET i.

v [It/511201" HIT/Inlay J. G. BLESSING. ALTERNATING CURRENT FREQUENCY METER. APPL |CAT|0N FILED FEB. 19. 1917.

1,355,884. I Patented Oct. 19, 1920.

IzzuEnZUr" FzZZurnsy UNITED, STATES PATENT OFFICE.

JOHN G. BLESSING, or cIIIoAGo, ILLINoIs, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, or CHICAGO, IL INOIs, A CORPORATION or ILLINOIS.

ALTERN'ATINGr-GURRENT FREQUENCY-METER.

Specification of Letters Patent. Patent ed Oct, 19, 1920.

Application filed February 19, 1917. Serial No. 149,399.

To all whom it may concern:

Be it known that I, J OHN G. BLEss No, a

citizen of the United States of America, and

periodicity of alternating currents, and the objects of my improvement are to incorporate in one instrument a meter and a timing device for automatically throwingit in and out of circuit, thereby eliminating all chance for human error; to provide afrequency meter which is direct reading, thereby avoiding the necessity of computation; to provide a frequency meter operating on a very short time interval, and in which the indicating hand is automatically reset at the beginning of each operation, whereby readings may be taken with great rapidity; and to provide otherimprovements tending to increase the accuracy, efficiency, and general usefulness of a device of this character.

The foregoing and other useful objects are attained through means which will be fully described and explained hereinafter, reference being had t the accompanying drawings.

In the drawings, Figure 1 is a front view of my improved frequency meter, assembled and ready for use; Figs. 2 and 3 are front and back views, respectively, of the mechanism with the casing removed; and Fig. 4: is a View taken inthe same direction as is Fig. 8, but having certainparts removed in order to show the timing device.

Referring to Fig. 1, in itsprefered embodiment the invention comprises a flanged casing 1 containing the frequency meter proper, a numbered dial 2 mounted on the front of the casing, an indicating hand 7,

and a glass front secured inplace by the rim. 8. Other exterior features are the operating lever 6, and the binding posts 4 and 5,by means of which latter the meter may be connected to the alternating current source whose frequency is to be ascertained.

When the casing is removed the meter mechanism itself appears in-the form shown.

clearly in Figs. 2 and 3. The different parts are mounted in aframecomprising the front plate 7 (Fig.2) and the back plate 8 (Fig. 3) which are separated the proper distance and rigidly connected by the bolts 9, 10, and 11. IToles are drilled opposite each other in the two frame plates to provide bearings for the shafts carrying the various gear wheels and levers, as is customary in ordinary clock-work. In fact,

the meter mechanism resembles very much a common type of clock movement in its mechanical construction, and for this reason unnecessary details of well known expedients in this art will be omitted.

The frequency meter may very" properly be divided into two distinct mechanlsms. The first comprises the train of gears which are driven by the electro-mlagnet of the device for the purpose of operating the indicating hand 7 and constitutes a register for counting the number of alternations or cycles; while the second comprises a timing .to Fig. 3, the electromagnet of the device comprises a laminated core 12 and two coils 15. The core. 12 is secured to the frame plate 7 by means of screws 13 and 14, heavy brass washers (not shown) being inserted between the core and. the frame plate to provide a proper clearance for the magnet coils. The armature 16-is supported. on pivot screws 21 and 22 which pass through studs formed of upturned portions of the frame plate 7. The armature is normally held against the adjustable stop 24: by a stiff spring-23, which latter is clamped under'the head of the bolt 11. 1 The armature 16 is preferably made as light as possible to reduce its inertia and thereby enable it to respond to currents of reasonably high frequency. -Two pawls are provided which engage oppositely inclined sets of ratchet teeth on the ratchet wheel. 25. i The pawl 17 isthe driving pawl. It; advances the ratchet wheel 25 one step in-a clock-wise direction y for each energization and deenergizationof the operating eleGtro-magnet. The pawl 19 itslupper bearing in the bridge 29.

is provided to insure against overrunning of the ratchet wheel. Retrograde movement of the ratchet wheel is prevented by the spring 18 -which ;engages the "same set of ratchet teeth as does the pawl 1-7. v v

. On the same shaft with. the ratchet wheel is mounted a pinion wheel 26 (Fig. '2)

which meshes with thogear wheel 27. The" gear wheel27' is carried by the shaft 28,

which has its lower bearing in, the frame plate 8 (just behind pawl 17 in Fig. 3) Iand ust above the bridge 29 the shaft 28 has rigidly ailixed to it a heart shaped cam 30,.while above the cam, allowing amply sufficient space for the dial, is attached'the indicating hand 7.

It may be mentioned that when the device is assembled the dial is clamped against the ends of the bolts 9, 10, and 11,. and is'supported at the center by a hub 31" on the cam 30., The shaft28 passes up through the dial and supports the hand 7 the roller 34 will engage theicam 30 and.

thehand is thereby returned to the position a short distance above it. While the cam 30 and, the hand Tare preferably rigid with the shaft-28, the gear wheel 27 is friction-ally mounted thereon so as'to permit restoration of the hand Without movement of the gears.

This restorationis accomplished by means of the operating lever 6, which alsoserves to store up power in andistart the time 'mechanism as will be subsequently described.

The lever 6 is rigidly mounted on a shaft Y 32, towhich'is also rigidly attached a lever 33 carrying at its extremity. the roller When the hand 7 is displacedfrom its nor mal position, and the lever 6 is pulled down,

shown in Fig. 2. p I

Having described the mechanical construction of .the registering portion of the frequencymeter, I will now proceed to a consideration of the timing mechanism, reference being had particularly to .Figs. 2

and 4. The timing device consists essen-' tially of an escapement wheel 46, pallets 49 and 50 coiiperating therewith, an escapement lever 48, and the balance wheel. 60. Time mechanism similar to' the above is 'well' known and needs no detailed description; Power for driving the escapement is stored in the'spring 45 and is communicated to theshaft on which the escapement wheel 46 is mounted through the medium ofa member 42, the ratchet 41, a spring pawl 43, and the gear wheel 40, the latter being i'n mesh with a pinion mounted onithe same shaft withithe escapement wheel. More in detail the member 42 and ratchet 41 are rigidly mounted on the shaft 53, while the gearflwheel40 is loosely mounted on the same shaft, The spring 45 is normally under tension: and' 'holds the member 42' in .the position shown-in the drawing with its toe 55 resting against the escapement wheel The operating shaft. In this position a pin 47 on the side of the escapement wheel rests against the end of member 42. The shaft 32 on which the operating lever 6 is mounted carries also a lever 35.

7 When the operating lever is pulled down, the end of lever 35 engagesa roller 44 on member 42 and rotates said the.pin 47.,so that when the operating lever is released the mechanism begins to run, power being supplied by the tensioned spring '45 as before mentioned- The gear 1 ratio between the gear wheel 40 and the pinion it engages is such that by the time the escapement wheel 46 (and its pinion) hasmade a complete rotation the member 42 will have returned to its starting point, and the escapement wheel. is stopped by the engagement of its pin 4-7 withtheend of said member. To sum up briefly, each time mechanism is started, and it continues to the, operating lever is. actuated the time run until-the escapement wheel has made one complete rotation.

I Mounted on the shaft which carriesthe escapement wheel 46' and its pinion are two cams '56 and 57'whieh are perhaps best seen in Fig. 2. These cams are provided for the [purpose of controlling. the contact springs 51 and. 52. .The endof spring 51' rides on theperiphery of cam, 57 while the endof spring 52'rides on the periphery of cam 56.

Throughout the greater portion .of its, cir-,

cumference cam 57 is lower, than cam 56 whereby spring 51 s permittedtomake contact with spring- 52 ;but for a short'distance,

by reason of a depression in cam 56 and a projection 011mm 5.7, thetwo cams are, of equal height, and the Contact springsyare se )arated. 7

connected across the two'bindi-ng posts 4 and 5 in series with the contact springs 51 andf52. 'VVhe'n it is desired to test the frequency of an alternating current, conmagnet 15' is of course nectionsare made ito'the bindingposts 4 i and 5iofithe frequencylmeter and theoper ating lever 6 is depressed .moin ent'arily. This operation restores the indicating hand 7 to zero (if it is not already there) and also starts the time mechanism.HReferring: to. Fig. 2, the cams 56 and 57will be ro-' tated in a clock-wise direction, and; as soon as contact spring 51 slips off theprojection on 'cam 57 the-circuit of the magnet 15' will be closed. The registering mechanism instantly starts and continuesto run until the contact spring 52 drops into the-depression oni'cam' 56, whereby the circuitiisi im,

terru ptedr This occursljust'before the pin cial frequencies with. the maximum convenience; but, as shown in Fig.1, it has been designed especially for testing the fre-.

quency of the ringing currents in harmonic signaling systems. These frequencies ordinarily are 16%, 33%; 50, and 66% cycles per second. The gear ratios in the registering mechanism are as follows: ratchet wheel 25, 100 teeth; pinion 26, 8 teeth; and gear wheel 27, 64 teeth. VVith these values, it will require 800 actuations of the magnet 15 to bring about one complete rotation of the hand 7. Since the magnet 15 responds twice to each cycle (on both the positive and negative waves), one complete rotation of the hand 7 will indicate 400 cycles.

The time mechanism of the meter is care fully regulated so that the duration of the closure of contact springs 51 and. 52 is'exactly 6 seconds; Owing to the peculiar cam construction for closing and opening these springs, and owing also to the fact that the mechanism runs long enough to attain synchronism before the springs are closed, this regulation can be accomplished with great accuracy. The running time being 6 seconds, the dial is calibrated by dividing the total number of cycles corresponding to different positions of the handby 6, the

results representing corresponding frequen-' cies, and being marked on the dial at such positions. For example, the numbeu 400 represents the number of cycles required to produce one rotation of the hand. The number 400 divided by'G gives as a quotient 66%, and the zero point on the diali's marked accordingly. Again, 300 cycles will produce just three fourthsof one rotation, and the dividing line between the third and fourth quadrants is therefore marked with the quotient obtained on dividing 300 by 6, which is 50. Other values may obviously be found in the same manner and the distance between them subdivided to give a complete scale...

It is to be understood, as before men'- tioned, that I do not wish to limit myself to the exact values herein specified, but contemplate the use of other time intervals and gear ratios as occasion may demand, in order to obtain dial calibrations suited to any commercia frequencies of alternat ing current.

Having described my invention, what I tected by Letters Patent will be pointed out in the appended claims.

What I claim as my invention is:

1. In a frequency meter, the combination with an indicating device and actuating means therefor comprising an electromagnet, of a circuit for saidmagnet, a time mechanism, manually operated means for winding said mechanism and for initiating the operation thereof, and means controlled by said mechanism effective after it has attained its normal speed for closing said circuit.

2. In a frequency meter, the combination with an indicating device and actuating means therefor comprising an electromagnet, of a circuit for said magnet, a time mechanism, manually operated means for winding said mechanism and for initiating the operation thereof, a circuit closing device controlled by said mechanism in its operation to close said circuit for a predetermined length of time, said circuit controller so adjusted as to hold the magnet circuit open until after said mechanism has reached its normal speed. i

3. In a frequency meter, the combination with a frequency indicator, of alternating current mechanism including a magnet for actuating said indicator, a circuit for said magnet, and a time mechanism for closing and opening said circuit, and a device for winding the time mechanism and restoring the indicator to the starting point simultaneously. r a

4. In a frequency meter, the combination with a register calibrated in cycles per second, and having an indicator, of alternating current mechanism and a circuit for operating said mechanism, a time mechanism' for closing and opening said" circuit, and a device for winding the time mechanism and restoring the indicator to the starting point simultaneously.

5. In a frequency meter, the combination with an alternating current circuit and mechanism for counting the cycles therein having an indicator, of power operated mechanism for closing said circuit a definite length of time, whereby said counting mechanism registers directly in cycles per second, a hand operated member, and means controlledthereby for supplying energy to said mechanism and for restoring the indicator after its operation.

'6. In a frequency meter, the combination with an indicating device, of mechanism ineluding a magnet for operating said device,

a circuit for said magnet, a time mechanism for closing and opening said circuit, a hand operated member, and means controlled thereby for winding the time mechanism and restoring the indicating device to its starting point.

7. In a frequency meter, the combination With'an electric current frequency indicat- 1ng device having an indicator, of mecha-' nism including a magnet responsive to alternating current for moving said indicator, a circuit for said magnet, a'time mechanism for closing and opening said circuit, and manually operated means for storing energy in said time mechanism and for initiating the operation of the same. 7

8. In a frequency meter, the combination 7 with an electric frequency indicator, of alternating current mechanism including a magnet responsive to alternating current forsetting said indicator, a circuit for said magnet, a time mechanism for-closing and opening said circuit, and manually operated means forstormg energy in said time mech-' anism and for initiating'the operation of the same. a

'9. In a frequency meter, the combination with a register graduated in cycles per sec- 0nd,'0f alternating current mechanism and a circuit for operating said register, a time mechanism for closing and opening said cir cuit, and-manually operated means for storing energy in said time mechanism and for initiating the operation of the same.

10. In a frequency meter, the combination with an indicating device, of mechanismvincluding a magnet for operating said device, 7

a circuit for said magnet, a time mechanism for closing and opening said circuit, manu' ally operated means for starting said time mechanism, and means for returning said indicating device to zero whenever said manually operated means is actuated.

7 l1.- In a frequency meter, the combination with an indicating device, of mechanism including'a magnet for operating said device, a circuit forsaid magnet, a time mechanism for closing and opening said circuit, manu-' allyvoperated means for storlng energy in said time mechanism and for initiating the operation of thesame, and means for returningsaid indicating device to zero whenever said rlnanually operatedmeans. 1s actuated. a q a 12. In a frequency meter, the combination with a frequency indicator, of alternating tuated.

current mechanism including'a magnet for setting said indicator, a circuit for said magnet, a time mechanism for closing, and opening said circuit, manually operated means for storing energy in said time mechanism and for initiating the operation of the same, and means for returning said indicator to zero whenever said manually operated means is actuated. r i

13. In a frequency meter, the 'combinationj with a register graduated in cycles per sec- 0nd, of alternating current mechanism anda circuit for operating said register, a-time mechanism for closing and openingsaid cir-c cuit, manually operated means for Storing energy in said time mechanism and for initiating the operation of the same, and

means for returning said register to zero whenever said manually operated means is actuatedr V '14. In a meter, adial and a movable pointer, mechanism for setting said pointer, time mechanism for starting said setting mechanism, means for starting said time mechanism, and means for resetting said pointer whenever said-time mechanism is started.

15. In a frequency meter, the combination I with a dial and-a pointer, of'mechanism:

so I

mechanism, and means'for resetting said means for resetting said pointer whenever-i said member is actuated. j

Signed by me at Chicago, Coolrcounty, State of Illinois, this 14th :day' of February,

, JOHN Bnnssmq 

